Micro - Antimicrobials (Part 1) Flashcards Preview

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Flashcards in Micro - Antimicrobials (Part 1) Deck (121)
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1
Q

How do imipenem, aztreonam, and cephalosporins work?

A

They block cell wall synthesis by inhibiting cross-linking of peptidoglycans

2
Q

How do bacitracin and vancomycin work?

A

They block peptidoglycan synthesis

3
Q

What antibiotic works by disrupting bacterial/fungal cell membranes?

A

Polymyxins

4
Q

Sulfonamides and trimethoprim work by blocking the synthesis of what molecules?

A

Nucleotides

5
Q

How do fluoroquinolones exhibit their antibacterial effects?

A

DNA topoisomerase inhibition

6
Q

Rifampin blocks the synthesis of what bacterial molecule?

A

mRNAs

7
Q

Chloramphenicol works by what mechanism?

A

It binds to the 50S ribosomal subunit and blocks the synthesis of protein

8
Q

Lincosamides work by what mechanism?

A

They bind to the 50S ribosomal subunit and block the synthesis of protein

9
Q

Streptogramins work by what mechanism?

A

They bind to the 50S ribosomal subunit and block the synthesis of protein

10
Q

Linezolid works by what mechanism?

A

It binds to the 50S ribosomal subunit and blocks the synthesis of protein

11
Q

Macrolides work by what mechanism?

A

They bind to the 50S ribosomal subunit and block the synthesis of protein

12
Q

Tetracyclines work by what mechanism?

A

They bind to the 30S ribosomal subunit and block the synthesis of protein

13
Q

Aminoglycosides work by what mechanism?

A

They bind to the 30S ribosomal subunit and block the synthesis of protein

14
Q

Name six antibiotics that are bacteriostatic.

A

Erythromycin, Clindamycin, Sulfamethoxazole, Trimethoprim, Tetracyclines, and Chloramphenicol (remember: were ECSTaTiC about bacteriostatics)

15
Q

Name six antibiotics that are bactericidal.

A

Vancomycin, Fluoroquinolones, Penicillin, Aminoglocysides, Cephalosporins, and Metronidazole (remember: Very Finely Proficient At Cell Murder)

16
Q

Penicillin _____ is administered intravenously; penicillin _____ is administered orally.

A

G; V

17
Q

Penicillin is the prototype for which class of antibiotics?

A

β-Lactams

18
Q

Penicillin blocks _____ to inhibit cross-linking and activates _____ enzymes as well.

A

Transpeptidase; autolytic

19
Q

Which types of bacteria are killed by penicillin?

A

Gram-positive cocci and rods, gram-negative cocci and spirochetes; bacteria with penicillinase are resistant

20
Q

What are the two major toxicities associated with penicillin treatment?

A

Hypersensitivity reactions and hemolytic anemia

21
Q

Methicillin, nafcillin, and dicloxacillin have the same mechanism of action as what class of antibiotics?

A

Penicillins

22
Q

What differentiates methicillin, nafcillin, and dicloxacillin from penicillin?

A

Methicillin, nafcillin, and dicloxacillin are resistant to penicillinase and are effective against bacteria like Staphylococcus aureus

23
Q

Methicillin, nafcillin, and dicloxacillin are resistant to penicillinase as a result of what difference in their structure?

A

A bulkier R group

24
Q

Methicillin, nafcillin, and dicloxacillin are narrow-spectrum antibiotics that are used clinically for the treatment of what conditions?

A

Staphylococcus aureus infections, except methicillin-resistant Staphylococcus aureus (remember: naf for staph)

25
Q

Why are nafcillin and dicloxacillin ineffective against methicillin-resistant Staphylococcus aureus?

A

Because of altered penicillin-binding protein target sites

26
Q

What are the two major toxicities associated with methicillin treatment?

A

Hypersensitivity reactions and interstitial nephritis

27
Q

Which drug can be administered with ampicillin to make it more effective against penicillinase-producing organisms?

A

Clavulanic acid, an inhibitor of penicillinase

28
Q

Which has greater oral availability: amoxicillin or ampicillin?

A

AmOxicillin has better Oral availability

29
Q

Which drugs have a wider spectrum of effectiveness: ampicillin/amoxicillin or penicillin?

A

Ampicillin and amoxicillin have a broader spectrum of effectiveness (remember: AMPicillin is Amped up penicillin)

30
Q

What are the three major toxicities caused by ampicillin and amoxicillin?

A

Hypersensitivity reactions, rash, and pseudomembranous colitis

31
Q

In addition to some gram-positive bacteria, which gram-negative rods are susceptible to ampicillin and amoxicillin?

A

H. influenzae, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, enterococci (remember: ampicillin/amoxicillin HELPS kill enterocicci)

32
Q

True or False? Ticarcillin, carbenicillin, and piperacillin are resistant to penicillinase.

A

False; but they can be used with clavulanic acid to give them resistance to penicillinase

33
Q

Which bacteria are ticarcillin, carbenicillin, and piperacillin active against?

A

Gram-negative rods, including Pseudomonas (remember: Ticarcillin, Carbenicillin, and Piperacillin Takes Care of Pseudomonas)

34
Q

What is a common toxicity of ticarcillin, carbenicillin, and piperacillin?

A

Hypersensitivity reactions

35
Q

Cephalosporins belong to what class of drugs?

A

-Lactams

36
Q

Are cephalosporins more or less susceptible to penicillinase than other β-lactams?

A

Less susceptible

37
Q

Name two examples of first-generation cephalosporins.

A

Cefazolin and cephalexin

38
Q

First-generation cephalosporins cover which organisms?

A

Gram-positive cocci, Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae. (remember: PEcK)

39
Q

Name three examples of second-generation cephalosporins.

A

Cefoxitin, cefaclor, and cefuroxime

40
Q

Second-generation cephalosporins cover which organisms?

A

Gram-positive cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria, Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens (remember: HEN PEcKS)

41
Q

Name three examples of third-generation cephalosporins.

A

Ceftriaxone, cefotaxime, and ceftazidime

42
Q

Third-generation cephalosporins cover which organisms?

A

Serious gram-negative infections that are resistant to other β-lactams

43
Q

Why are third-generation cephalosporins a good choice for treatment of meningitis?

A

Because they penetrate the blood-brain barrier

44
Q

Which third-generation cephalosporin is used for Pseudomonas coverage?

A

Ceftazidime

45
Q

Which cephalosporin is often used to treat gonorrhea?

A

Ceftriaxone

46
Q

Name one example of a fourth-generation cephalosporin.

A

Cefepime

47
Q

Fourth-generation cephalosporins are different from third-generation cephalosporins in that the fourth-generation drugs have increased activity against which organisms?

A

Pseudomonas and gram-positive organisms

48
Q

True or False? Unlike penicillin, hypersensitivity reactions are not a major toxicity of cephalosporins.

A

False; hypersenstivity reactions are a potential toxocity of all cephalosporins

49
Q

What is the likelihood that a penicillin-allergic patient is also allergic to cephalosporins?

A

There is cross-hypersensitivity in 5% to 10% of patients

50
Q

What toxicity can occur in patients using cefamandole who drink alcohol?

A

A disulfiram-like reaction (applies to all cephalosporins with a methylthiotetrazole group)

51
Q

Aztreonam is an example of what subclass of β-lactam drugs?

A

Monobactams

52
Q

Is aztreonam susceptible to β-lactamases?

A

No; it is resistant to β-lactamases because it is a monobactam

53
Q

Aztreonam inhibits cell wall synthesis by binding to what substance?

A

Penicillin binding protein 3

54
Q

Aztreonam is synergistic with what class of drugs?

A

Aminoglycosides

55
Q

Does aztreonam have any cross-allergenicity with penicillins?

A

No

56
Q

Aztreonam is used to treat infection with what type of organisms?

A

Gram-negative rods (Klebsiella, Pseudomonas, and Serratia)

57
Q

Which gram-positive and anaerobic bacteria does aztreonam have activity against?

A

None!

58
Q

Aztreonam is used in which two patient groups who have infections caused by susceptible organisms?

A

Penicillin-allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides

59
Q

Aztreonams toxicity profile includes what side effects?

A

Aztreonam is usually nontoxic, although it may occasionally cause gastrointestinal upset

60
Q

Imipenem is an example of what subclass of -lactams?

A

Carbapenems

61
Q

Imipenem is a _____(broad-/narrow-) spectrum, β-lactamase-_____ (resistant/susceptible) carbapenem.

A

Broad; resistant

62
Q

Imipenem is always administered with _____ to reduce inactivation in the _____ _____

A

Cilastatin; it is given to reduce inactivation in renal tubules (remember: the "kill is Lastin with ciLastin)

63
Q

Cilastatin is an inhibitor of what substance and thus given with imipenem?

A

Renal dehydropeptidase I

64
Q

Imipenem is used to treat which kinds of infections?

A

Gram-positive cocci, gram-negative rods, and anaerobic infections

65
Q

Imipenem/cilastatin and meropenem are the drugs of choice for infection by which bacteria?

A

Enterobacter

66
Q

At what point during disease progression is imipenem or meropenem considered a treatment option? Why?

A

Only when other medications have failed or in life-threatening infections because of the significant adverse effects these two medications have

67
Q

What are the toxicities associated with imipenem and meropenem?

A

Gastrointestinal distress, rashes, and seizures; adverse effects more commonly occur at high doses

68
Q

Which has a higher risk of causing seizures imipenem or meropenem?

A

Imipenem

69
Q

Why is meropenem not coadministered with cilastatin?

A

Because meropenem is stable to dehydropeptidase I

70
Q

How does vancomycin work?

A

It binds the D-Ala D-Ala portions of cell wall precursors, thereby inhibiting cell wall mucopeptide formation

71
Q

How do bacteria develop resistance to vancomycin?

A

Conversion of D-Ala D-Ala to D-Ala D-Lac

72
Q

Vancomycin is used for multidrug-resistant gram-_____ (positive/negative) organisms.

A

Positive

73
Q

Name two organisms for which vancomycin is commonly used.

A

Methicillin-resistant Staphylococcus aureus and Clostridium difficile (pseudomembranous colitis)

74
Q

What types of toxicity are possible with vancomycin treatment?

A

Nephrotoxicity, ototoxicity, thrombophlebitis, and diffuse flushing ("red man syndrome"), but in general it does NOT cause many problems

75
Q

"Red man syndrome" with vancomycin administration can largely be prevented with pretreatment with _____ and with the use of a _____ (slow/fast) infusion rate.

A

Antihistamines; slow

76
Q

Which protein-synthesis-inhibiting antibiotics are bactericidal?

A

Aminoglycosides

77
Q

Which mnemonic addresses which protein synthesis inhibitors are 30S subunit inhibitors and which are 50S subunit inhibitors?

A

Buy AT 30, CCELL at 50 (Aminoglycosides and Tetracyclines at 30, Chloramphenicol, Clindamycin, Erythromycin, Lincomycin and Linezolid at 50)

78
Q

Name five aminoglycoside antibiotics.

A

Gentamicin, neomycin, amikacin, tobramycin, and streptomycin

79
Q

Aminoglycosides block protein synthesis by the inhibition of _____ _____ formation, and they cause the misreading of _____.

A

Initiation complex; mRNA

80
Q

Aminoglycosides require _____ for uptake and therefore are ineffective against _____.

A

Oxygen; anaerobes (remember: the aminoglycosides (Mean) gentamicin, neomycin, amikacin, tobramycin, and streptomycin (GNATS) can NOT (Nephrotoxicity, Ototoxicity and Teratogen) kill anaerobes

81
Q

Are gentamicin, neomycin, amikacin, tobramycin, and streptomycin bactericidal or bacteriostatic?

A

Bactericidal

82
Q

Aminoglycosides are used to treat severe infections by gram-_____ (negative/positive) _____ (cocci/rods).

A

Negative; rods

83
Q

Aminoglycosides are synergistic with which class of antibiotics?

A

-Lactams

84
Q

Neomycin is commonly used as part of preparation for what procedure?

A

Bowel surgery

85
Q

What toxicities are associated with aminoglycosides?

A

Nephrotoxicity and Ototoxicity; they are also Teratogenic (remember: mean GNATS can NOT kill anaerobes = Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin)

86
Q

Aminoglycosides’ nephrotoxic potential is increased when it is used with what class of antibiotics?

A

Cephalosporins

87
Q

Aminoglycosides’ ototoxic potential is increased when it is used with what class of drug?

A

Loop diuretics

88
Q

Name four antibiotics that belong to the class tetracyclines.

A

Tetracycline, doxycycline, demeclocycline, and minocycline

89
Q

What is the mechanism of action of tetracyclines?

A

Tetracyclines bind to 30S and prevent the attachment of aminoacyl-tRNA

90
Q

Do tetracyclines have good central nervous system penetration?

A

No; tetracyclines have limited central nervous system penetration

91
Q

Which tetracycline-family drug is safe to use in patients with renal failure?

A

Doxycycline (fecally eliminated and therefore can be used by patients with renal failure)

92
Q

Which foods and drugs should not be taken with tetracyclines? Why?

A

Milk, antacids, and iron-containing preparations, because divalent cations inhibit the absorption of doxycycline

93
Q

Tetracyclines are used to treat infections with which two organisms that are transmitted by ticks?

A

Borrelia burgdorferi and Rickettsia

94
Q

Tetracyclines are used to treat which skin infection?

A

Acne

95
Q

Tetracyclines are avoided for use in children for what three reasons?

A

They discolor teeth, inhibit bone growth, and cause gastrointestinal distress

96
Q

What dermatologic adverse effect results from use of tetracyclines?

A

Photosensitivity

97
Q

Which tetracycline is used as a diuretic in patients with the syndrome of inappropriate antidiuretic hormone secretion?

A

Demeclocycline, because it is an antidiuretic hormone antagonist (remember: Demeclocycline = Diuretic)

98
Q

Name ten bacteria that tetracyclines are active against.

A

Vibrio cholerae, Acne, Chlamydia, Ureaplasma, Urealyticum, Mycoplasma pneumoniae, Tularemia, Helicobacter pylori, Borrelia burgdorferi, Rickettsia (remember: VACUUM THe Bed Room)

99
Q

Can pregnant women take tetracyclines?

A

No; tetracyclines are contraindicated in pregnancy

100
Q

Name three examples of macrolide antibiotics.

A

Erythromycin, azithromycin, and clarithromycin

101
Q

Macrolides inhibit protein synthesis by binding to the _____ rRNA of the _____ (30S/50S) ribosomal subunit.

A

23S; 50S

102
Q

The binding of macrolides to the 23S rRNA of the 50S ribosomal subunit blocks what cellular process and inhibits protein synthesis?

A

Translocation of the peptide chain

103
Q

Macrolides are used to treat infection with which organisms?

A

Gram-positive cocci, Mycoplasma, Legionella, Chlamydia, and Neisseria

104
Q

What three types of infections are treated with macrolides?

A

Upper respiratory infections, pneumonia, and sexually transmitted diseases

105
Q

Streptococcal infections in patients who are allergic to penicillin are treated with which drugs?

A

Macrolides

106
Q

What is the most common cause of noncompliance with macrolide treatment?

A

Gastrointestinal discomfort

107
Q

Macrolides increase the serum concentration of which drugs?

A

Theophyllines and oral anticoagulants

108
Q

Other than gastrointestinal upset, what are four other adverse effects of macrolides?

A

Acute cholestatic hepatitis, eosinophilia, skin rashes, and prolonged QT interval

109
Q

Which macrolide antibiotic is most likely to cause a prolonged QT interval?

A

Erythromycin

110
Q

Chloramphenicol inhibits the enzyme _____, which is part of the _____ (30S/50S) ribosomal subunit.

A

Peptidyltransferase; 50S

111
Q

Chloramphenicol is used to treat what type of infection?

A

Meningitis; it is considered a last resort because of significant toxicities

112
Q

Chloramphenicol is used to treat meningitis caused by what three organisms?

A

Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae

113
Q

What are the three major toxicities of chloramphenicol?

A

Dose-dependent anemia, dose-independent aplastic anemia, and gray baby syndrome

114
Q

Chloramphenicol causes gray baby syndrome in _____ _____ as a result of the lack of the liver enzyme _____-_____ _____.

A

Premature infants, UDP-glucuronyl transferase

115
Q

At the 50S ribosomal subunit, clindamycin inhibits protein synthesis by blocking the formation of what?

A

Peptide bonds

116
Q

Clindamycin is primarily used to treat what type of organisms?

A

Anaerobes such as Bacteroides fragilis and Clostridium perfringens

117
Q

What are the three major toxicities associated with clindamycin?

A

Pseudomembranous colitis, fever, and diarrhea

118
Q

Why does pseudomembranous colitis often occur following treatment with clindamycin?

A

Because it kills normal flora and allows overgrowth of Clostridium difficile

119
Q

Name three sulfonamide antibiotics

A

Sulfamethoxazole, sulfisoxazole and sulfadiazine

120
Q

What are sulfonamide antibiotics and how do they work?

A

They are para-aminobenzoic acid antimetabolites that stop the activity of dihydropteroate synthetase, preventing DNA synthesis

121
Q

Sulfonamides are active against what organisms?

A

Gram-positive organisms, gram-negative organisms, Nocardia, and Chlamydia